Page:Popular Science Monthly Volume 60.djvu/144

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POPULAR SCIENCE MONTHLY.

workshop or has contrasted a first-class English shop where this is the practice with an old-fashioned establishment where standardization is hardly known, can have no hesitation on this question. It has its disadvantages, less is left to the originality of the workman and in consequence they lose the power of adaptation to new circumstances and conditions. The English mechanic is I believe greatly superior to the German, but the scientific organization of the German shops enables them to compete successfully with the English.

In 1881 the German Association of Mechanics and Opticians was formed, having for its aim the scientific, technical and commercial development of instrument making. The society has its official organ, the 'Zeitschrift für Instrumentenkunde,' edited by one of the staff of

PSM V60 D144 Section of iron after various treatments.png
Section of Iron after Various Treatments.
Specimen.

1. Raised to 1000°. Worked and cooled slowly. Masses of carbide ground work, bands of iron and carbide, pearlite structure.

2. Raised to 850° and quickly cooled. Masses disappear.

3. Raised to 850° and quenched in water. Arcicular structure. Martensite, hard steel.

4. Raised to 1050° and quenched in iced brine. Martensite and Austenite.

5. Same cooled in liquid air to—243. Much like martensite.

6. Heated to near melting point, quenched suddenly burnt steel.

7. Heated to 650°—annealed for a long time at this temperature and slowly cooled, bands of carbide and pearlite.

8. Any specimen except 6 heated to 850, worked and slowly cooled, giving us the structure 1.

Very marked changes might have been produced in 3 by annealing at 140°.